Locking device and a line fitting provided therewith

ABSTRACT

A locking device ( 1 ) is fixed to a nut ( 4 ) and includes a coupling unit ( 42 ) insertable into a hexagonal configuration ( 11 ) of a spigot end ( 2 ) at a reduced axial distance being coupled by mutually interpenetrable gears ( 49, 51 ) with a stop unit ( 38 ) which axially slides in a body ( 18 ) opposite to a compression spring ( 36 ). The gears ( 49, 51 ) are symmetric and are insertable into each other with a predetermined elastic resistance by the action of compression or loosing torque. The device is embodied in one piece which is mounted by assembling with the nut without affecting the spigot ends ( 2, 3 ).

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a locking device for two components which arein a mutual screw connection.

This invention also relates to a pipe coupling provided with such adevice.

The function of the locking device is to prevent undesirable unscrewingof the two components from each other, in particular in applicationswhere the two components are subject to vibrations or shaking duringuse.

The invention is more particularly but not limitatively aimed atstandardized couplings comprising a nipple at the end of one of thepipes, intended to be pressed into a flaring of the end of the otherpipe, by tightening a nut captively mounted on one of the pipes andengaging a thread formed on the other pipe.

2. Description of Related Art

U.S. Pat. No. 6,293,595 B1 describes such a locking device capable ofsimultaneously engaging, by an axial movement under pressure from aspring, the hexagonal formation of the nut and a stop component integralwith the male end-portion of the pipe. In order to be able to separatethe two pipe end-portions, the coupling component must be pushed backagainst the return spring to the position where it is disconnected fromthe hexagonal formation provided on the nut and/or from the stopcomponent attached to the male end-portion of the pipe.

During screwing or unscrewing, the presence of the tool on the nutprevents the coupling component from returning to the locking position.As soon as the tool is withdrawn when the screwing operation iscompleted, the coupling component is free to move to the lockingposition through the action of the spring.

This known device has the considerable advantage of being able to beadapted to a standard pipe coupling without modifications other thanmerely securing a bearing element on the male end-portion of thecoupling.

In certain applications, where accessibility is difficult, in particularin aeronautics, it is desirable to minimize the interference caused bythe locking device. With the known device, if the nut resists theunscrewing force exerted by the operator, the operator, who cannot seethe nut, does not know whether the resistance is due to the screwingconnection itself or to an incorrect disengagement of the couplingcomponent. Moreover, and in any case, he must remember the structure ofthe locking device in order to displace his tool axially along thehexagonal formation thereby to push the coupling component back beforebeing able to perform the unscrewing operation strictly speaking.

BRIEF SUMMARY OF THE INVENTION

The object of this invention is to improve the known locking device interms of ease of use.

According to the invention, the locking device for a screw couplingcomprising a first and a second component which are rotatable inrelation to one another during the screwing, a first of the componentscomprising a first thread and a rotating engagement formation distantfrom this first thread, the locking device being mounted on the secondcomponent and comprising:

-   -   a coupling component for coupling with the engagement formation,    -   a stop component firmly connected for common rotation with a        body carried by the second component,    -   disconnectable coupling means between the coupling component and        the stop component,        is characterized in that the coupling means are of the type with        a ratchet allowing relative rotation in the direction of        unscrewing when a predetermined spring resistance is overcome.

According to the invention it has been found that a reversible ratchetsystem is very effective for preventing any unscrewing as a result ofvibrations. The ratchet only disconnects the two components from oneanother when a spring resistance has been overcome over a sufficientangular distance to reach the point passing over the apex of a ratchettooth. However the vibratory excitation in one direction or in the otheris of too short a duration for this process of passing over the toothapex to be possible. The process can certainly begin, but it is followedby a springing back to the most stable locking situation.

By contrast, when an intentional unscrewing is carried out, the operatoris not subjected to any feeling of malfunction or disturbance.

The unscrewing is therefore possible without the operator having toundertake special precautions or actions. He need only engage his toolwith the hexagonal or other engagement formation provided on the firstcomponent of the screw coupling, and actuate his tool as usual.

The locking device according to the invention can be designed to beentirely compatible with standard pipe couplings without these requiringmodifications other than fixing the device body onto the secondcomponent. Preferably, it is the nut which constitutes the secondcomponent. It is in fact easier to produce a special nut, in particularin the case of subsequent fitting. Moreover if the nut is equipped withthe device, the two end-portions can be completely cleared when they arein the uncoupled state, simply by sliding the nut far enough back alongthe pipe which carries it, and the locking device no longer forms anyobstruction to moving a pipe laterally in relation to the other.

According to a second aspect of the invention, the pipe couplingcomprising a pipe end-portion provided with an external thread and a nutwhich can be screwed onto the external thread and rotatably mounted onanother pipe end-portion, is characterized in that it also comprises alocking device according to the first aspect, for selectively lockingthe relative rotation of the two components constituted by the nut andthe end-portion provided with an external thread.

Other features and advantages of the invention will also become apparentin the following description, which relates to non-limitative examples.

BRIEF DESCRIPTION OF THE DRAWINGS

In the attached drawings:

FIG. 1 is an axial sectional half-view of a pipe coupling according tothe invention in the locking position, a first variant being illustratedfor the means of securing the locking device onto the nut;

FIG. 1A is a view similar to FIG. 1, but showing the other half of thepipe coupling according to the invention, and in the unlocking positionat the start of unscrewing or at the end of screwing, a second variantbeing illustrated for the means of securing the locking device onto thenut;

FIG. 2 is a perspective half-view of the locking device and of a part ofthe nut before mounting the device on the nut, the first variant for themeans of securing the locking device onto the nut being illustrated;

FIG. 2A is another perspective half-view of the locking device and of apart of the nut before mounting the device on the nut, the secondvariant for the means of securing the locking device onto the nut beingillustrated;

FIG. 3 is a partial sectional view along line III-III of FIG. 1;

FIG. 4 is a perspective view of the coupling and stop components, aswell as of a part of the spring; and

FIG. 5 is a view similar to the upper half-view of FIG. 1, but in thecase of a worn pipe coupling.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in FIGS. 1 and 1A, the locking device 1 according to theinvention can be adapted to a first pipe coupling comprising a maleend-portion 2- or nipple-, firmly attached to a first one of the pipesto be coupled, and a female end-portion 3, which is firmly attached tothe second one of the pipes to be coupled, as well as a nut 4.

The end-portions 2 and 3 comprise at their free end a male sealformation, with an ovoid shape 6 and respectively a female sealformation 7, with a frusto-conical shape, intended to leak-tightly bearon one another. Starting from the ovoid seal formation 6, the nipple 2comprises an external thread 8 then a flange 9 provided on its peripherywith a rotational engagement formation such as a hexagonal formation 11.The formation is distant or separated from the thread 8 of the component2 in the sense that this formation 11 which will be used for the lockingis not constituted by an alteration of the thread such as a flat sectionor a groove eliminating part of the threads.

The nut 4 comprises at its rear end, remote from the end-coupling 2, aninternal flange 12 and an external rotational engagement formation 13such as a hexagonal formation. The internal flange 12 is behind andengages a shoulder 14 of the end-portion 3. The shoulder 14 faces awayfrom the end-portion 2 in order to retain the nut 4 in a captivecondition and in order to receive from the nut 4 a force which causesthe seal formation 7 to leak-tightly engage the seal formation 6 of theend-portion 2.

The nut 4 is extended forwardly by a tube 32 which comprises startingfrom its front end turned towards the end-portion 2 an internal thread16 capable of cooperating with the thread 8 of the end-portion 2 inorder to produce the above-mentioned tightening pressure.

The locking device 1 according to the invention comprises a support body18—or cup—comprising at its rear end a sleeve 19 which is fitted aroundthe hexagonal formation 13 of the nut 4. To this effect, the sleeve 19comprises an internal surface 21 having a prismatic shape with ahexagonal contour which allows the sleeve 19 to be fitted, withpractically no play, onto the hexagonal formation 13 (see also FIG. 2).Once this fitting has been carried out, the nut 4 and the body 18 areconnected for common rotation. Moreover, the sleeve 19 is equipped withretaining means for axially attaching the sleeve 19 and therefore thebody 18 to the nut 4. These means comprise at the annular inner end ofthe surface 21 an internal flange 22 (FIG. 1) intended to abut a frontshoulder 23 of the nut 4, said shoulder adjacent to the front edge ofthe formation 13. In the version represented in FIGS. 1 and 2, theretaining means also comprise locking lugs 24 cut out in the wall of thesleeve 19 with essentially axial slits 26 opening though the rear edgeof the sleeve 19. The locking lugs 24 end in locking jaws 27 which, onceassembling is completed, grasp the rear face 28 of the nut 4, adjacentthe rear annular edge of the hexagonal formation 13.

In the embodiment shown in FIGS. 1A and 2A, the retaining means comprisecrimping tabs 29 which are initially in the extension of at least someof the faces of the inner surface 21 of the sleeve 19 (FIG. 2A). Onceassembling is completed, the tabs 29 are plastically bent back againstthe rear surface 28 of the nut 4, as shown at the bottom of FIG. 1.

The sleeve 19 has on its external surface its own hexagonal formation 25intended to substitute for the hexagonal formation 13 of the nut inorder to allow the nut to be rotated using a tool such as a wrench (notrepresented) when the device 1 is in place.

At its front end, the sleeve 19 is rigidly connected to and forms asingle piece with the rear end of a generally cylindrical skirt 31 whichextends around the tube 32 while forming an annular chamber 34 betweenthe skirt 31 and the tube 32.

Inside the chamber 34 there is, starting from the rear end thereof, ahelical compression spring 36 having the same axis 37 as the pipe, anannular stop component 38 around the axis 37 and comprising blocks 39slidingly mounted in axial grooves 41 of the internal wall of the skirt31, and finally a coupling component 42 comprising on its externalperiphery a boss 43 which prevents the coupling component 42 fromdisengaging from the skirt 31. To this effect, the boss 43 abuts aterminal rim 44 of the skirt 31, formed by plastic deformation,projecting radially towards the axis 37.

As particularly shown in FIG. 4, the coupling component 42 protrudesoutside the skirt 31 beyond the terminal rim 44 and has in its frontportion, which protrudes from the skirt 31 at least when the spring 36is in the state of relatively low compression, a hexagonal female recess46 with a size corresponding to that of the male hexagonal formation 11of the first component 2. The axial width of this recess is much smallerthan that of the hexagonal formation 11 and it is delimited, at its rearend, by stops 47 intended to engage a shoulder 48 adjacent the hexagonalformation 11. This engagement limits the axial extent by which therecess 46 covers the formation 11.

The axial dimensioning of the assembly is such that when the twoend-portions 2, 3 in a new condition (FIG. 1) are leak-tightly pressedaxially against one another by the clamping exerted by the nut 4, thecoupling component 42 engages the hexagonal formation 11, the stops 47engage the shoulder 48 while the stop 43 is almost bearing against therim 44.

As illustrated in FIG. 5, the generic type pipe couplings addressed bythe invention tend to become worn by radial contraction of the male part6, and widening or flaring out of the frusto-conical part 7. Thisresults in an increase in the travel of the nut 4 along the firstcomponent 2 which is necessary in order for the desirable axial clampingto be achieved. This is allowed for according to the invention by meansof a sufficient compression displacement of the spring 36, andsufficient initial axial mobility distances d (FIG. 1) between thecoupling component 42 and the free end of the nut 4, and D between therear end of the blocks 39 and the bottom of the chamber 34.

The stop component 38 and the coupling component 42 have on theirannular edges turned towards one another teeth 49, 51 pointing axiallyand having a symmetrical profile. In other words, in relation to acircumferential direction, the teeth, which have a triangularconfiguration, each have a front face and a rear face which have thesame oblique slope. Moreover, the teeth 49 of the stop component 38 andthe teeth 51 of the coupling component 42 have complementary profiles sothat they can interpenetrate as represented in FIG. 1 and in FIGS. 4 and5. By contrast, in FIG. 1A, the teeth are tip to tip.

It is very easy to provide a pipe coupling with the locking deviceaccording to the invention. The nut being completely separate from thefirst component 2, and the latter being separate from the secondcomponent 3, the device 1 is fitted onto the nut 4 from the front end ofthe nut 4 until the flange 22 abuts against the shoulder 23. In theself-locking embodiment, the lugs 24 are forced radially outwards inorder to pass the shoulder 23 then resiliently spring back inwardly whenthe jaws 27 can snap behind the face 28 of the nut 4. In the versionwith crimping tabs 29, the fitting is carried out without resistanceuntil the flange 22 abuts the shoulder 23. At this stage, the crimpingtabs 29 are bent back radially inwardly as represented at the bottom ofFIG. 1. It is noteworthy that the device 1 forms an assembly all in onepiece being entirely mounted on only one of the components to be lockedtogether, without requiring any arrangement on the other component.

In order to couple the pipe coupling, the nut 4 is screwed around thethread 8 of the end-portion 2 using a wrench which engages the hexagonalformation 11 of the end-portion 2 and another wrench which engages thehexagonal formation 25 of the device 1. The coupling component 42 abutsthe edge 44 through the action of the compression spring 36. As the endof screwing approaches, the coupling component 42 abuts the shoulder 48of the end-portion 2, the spring 36 starts to compress and then, as thecomponent 42 is driven in rotation by the interpenetration of the teeth49 and 51, its recess 46 ends up matching with the formation 11 of theend-portion 2 and the spring 36 springs back while causing the recess 46to fit onto the formation 11. The coupling component 42 is consequentlyprevented from turning with the nut 4 and the teeth 49 and 51 click oneon another, each time with a brief compression of the spring 36 when theteeth 49 and 51 are tip to tip as illustrated in FIG. 1A. Finally thesituation represented in FIG. 1 is reached, where the pipe is locked andleak-tight, and the nut 4 is prevented from turning under the effect ofvibrations or other parasitic loads thanks to the locking of the nut 4and the end-portion 2 via the body 18, the stop component prevented fromturning in relation to the body 18 thanks to the blocks 39 engaged inthe grooves 41, and the coupling component 42 prevented from turning inrelation to the stop component 38 because of the interpenetration of theteeth 49 and 51. If the rotation of the nut at the end of locking endsat a position where the teeth 49 and 51 are tip to tip as represented inFIG. 1A, any stress, vibratory or otherwise, can then only result in aslight turn of the nut until the situation of interpenetration of theteeth is achieved.

In order to unscrew the nut, it is sufficient to again position the twotools on the hexagonal formations 25 and 11, and to make the device 1and the nut 4 turn together in the direction of the unscrewing. Theteeth and 51 jump one above the other with brief compressions of thespring 36 until, as a result of the axial backward movement of the nut 4associated with the unscrewing movement, the coupling component 42 endsup being disengaged from the hexagonal formation 11 of the end-portion2. The coupling component 42 now turns with the nut 4 in the unscrewingdirection. Once unscrewing is completed, the nut 4 and the device 1 canmove together as far as desired rearwardly (therefore towards the leftside of FIGS. 1 and 1A) in order to allow the desired technicaloperation to be carried out on the coupling without any interference.

When the coupling is worn, the residual spring compression travel of thespring 36 and the distance D′ (FIG. 5) still allowed for the blocks 39in the locked state are sufficient to allow the teeth 49 and 51 to passeach other by a ratchet movement.

Of course, the invention is not limited to the examples described andrepresented.

The device could also be attached to the male end-portion 2 and becaused to cooperate, for locking, with the hexagonal formation 13 of thenut. This solution is less preferred because the device may then preventgood access to the components of the coupling such as the male andfemale end-portions even after unscrewing is completed.

If it is sought to have a different resistance of the teeth 49 and 51when screwing and unscrewing, they can be made asymmetrical but theymust always have a sufficiently small slope to be able to pass eachother simply by the action of a turning torque exerted on the lockingdevice 1 in relation to the other component which is not equipped withthe device.

It is also possible to produce pipe coupling components, and inparticular nuts which are directly equipped with a device according tothe invention, in which case the body 18 and the nut 4 can simplyconstitute one and the same part, or for example two parts assembledtogether in a permanent fashion, by welding or bonding, etc.

1. A screw coupling including a locking device, said screw couplingcomprising first and second components rotatable in relation to oneanother during screwing and unscrewing, the first component comprising afirst thread and a rotating engagement formation distant from the firstthread, the locking device being mounted on the second component andcomprising: a coupling component for coupling with the engagementformation, a stop component connected for common rotation with a bodycarried by the second component, the body connected for common rotationwith the second component, and disconnectable coupling means between thecoupling component and the stop component, wherein the disconnectablecoupling means comprises a ratchet allowing relative rotation in thedirection of unscrewing when a torque at least indirectly applied to thecoupling component and the stop component with respect to one anotherovercomes a predetermined elastic resistance, the torque between thecoupling component and the stop component resulting from a torqueapplied between the first component and the body.
 2. The screw couplingaccording to claim 1, wherein the disconnectable coupling meanscomprises axially pointing teeth formed on the coupling component and onthe stop component, which are urged towards one another by a spring inthe direction of teeth interpenetration.
 3. The screw coupling accordingto claim 2, wherein the coupling and stop components are axially movablein relation to the body and are commonly urged by the spring towards astop provided in the body for the coupling component.
 4. The screwcoupling according to claim 2, wherein the coupling component can bedrawn back against the spring and comprises a stop for engagement of ashoulder of the first component in order to limit the axial extent bywhich the coupling component is able to cover the engagement formation.5. The screw coupling according to claim 1, wherein the couplingcomponent can be drawn back against a spring and comprises a stop forengagement of a shoulder of the first component in order to limit theaxial extent by which the coupling component is able to cover theengagement formation.
 6. The screw coupling according to claim 1,wherein the body is formed as a cup enclosing the stop component andpartially enclosing the coupling component.
 7. The screw couplingaccording to claim 1, wherein the stop component and the couplingcomponent are mounted around a tube of the second component, which isinternally threaded for screwing with the first component.
 8. The screwcoupling according to claim 1, wherein the body can be fitted onto asecond engagement formation integral with the second component and thebody having an engagement formation which can be used in place of thesecond engagement formation in order to carry out the relative rotationof the first and second components by means of tools.
 9. The screwcoupling according to claim 1, wherein the body is secured onto thesecond component by snap-fit.
 10. The screw coupling according to claim1, wherein the body is secured onto the second component by crimping.11. The screw coupling according to claim 1, wherein the locking deviceis adapted to be mounted as a single unit onto the second component. 12.The screw coupling according to claim 1, being entirely mounted on thesecond component.
 13. A pipe coupling comprising a first pipeend-portion provided with an external thread, a second pipe end-portion,a nut which is rotatably mounted on the second pipe end-portion and canbe screwed on the external thread of the first pipe end-portion, and alocking device for selectively locking against relative rotation the nutand the first pipe end-portion provided with the external thread, thelocking device being mounted on the second pipe end-portion andcomprising: a coupling component for coupling with an engagementformation formed on the first pipe end-portion distant from the externalthread, a stop component for common rotation with a body carried by thenut, the body connected for common rotation with the nut, anddisconnectable coupling means between the coupling component and thestop component, wherein the disconnectable coupling means comprises aratchet allowing relative rotation in the direction of unscrewing when atorque at least indirectly applied to the coupling component and thestop component with respect to one another overcomes a predeterminedelastic resistance, the torque between the coupling component and thestop component resulting from a torque applied between the first pipeend-portion and the body.
 14. The pipe coupling according to claim 13,wherein the first and the second pipe end-portions and the nut arestandard non-modified components.